Combustor having enhanced weak extinction characteristics for a gas turbine engine

Abstract

A gas turbine engine combustor (16) is provided with an airspray fuel injector (24), the downstream end of which is coplanar with a heat shield (38) provided at the upstream end of the combustor (16). The fuel injector (24) injects a fuel and air mixture into the combustion chamber (16a) defined within the combustor (16) which is in the form of a cone having an angle greater than 130°. The combustor (16) has enhanced weak extinction characteristics.

We claim: 
     
       1. A gas turbine engine combustor comprising a combustion chamber (16) having an upstream heat-shield (38) surface with plural holes (42) therein for directing cooling air therethrough for flow over the downstream heat-shield (38) surface and having at least one fuel injector (24) for injecting a mixture of fuel and air into said combustion chamber (16), said fuel injector (24) being so configured that said fuel and air mixture is nominally injected about an axis into said combustion chamber (16) in the general form of a hollow cone (34) defined about the axis, characterized in that the angle (B) of said cone (34) and the velocity of said injected fuel and air mixture are arranged to be such that together they result in the injected fuel and air mixture creating a low pressure zone adjacent the heat shield (38) surface to cause said injected fuel and air mixture to flow generally away from the axis and parallel with said heat-shield surface (38), the hole (42) directing cooling air intermediate the heat shield (38) surface and the low pressure zone and at an angle relative the heat shield surface (38) so that the cooling air flow does not oppose said flow of said fuel and air mixture, at least some of said fuel and air mixture changing direction to flow toward the axis to effect a flow recirculation zone immediately downstream of the heat shield (38) surface. 
     
     
       2. A gas turbine engine combustor as claimed in claim 1 characterized in that the angle of said cone (34) is greater than 130°. 
     
     
       3. A gas turbine engine combustor as claimed in claim 1 or 2 characterized in that the downstream end of said fuel injector (24) is generally coplanar with the plane of the heat shield (38) surface of said combustion chamber (16). 
     
     
       4. A gas turbine engine combustor as claimed in claim 1 characterised in that the upstream end of said combustion chamber (16) is constituted by a bulkhead (19), the or each of said heatshields (38) being disposed downstream of said bulkhead (19) so as to be in spaced apart relationship therewith, means (39) being provided to direct cooling air into the space (40) defined between said bulkhead (19) and said the or each heatshield (38) so as to provide cooling of said the or each heatshield (38). 
     
     
       5. A gas turbine engine combustor as claimed in claim 4 characterized in that a plurality of holes (39) are provided in said bulkhead (19) to direct cooling air into said space (40) defined between said bulkhead (19) and said heat shield (38). 
     
     
       6. A gas turbine engine combustor as claimed in claim wherein said at least one fuel injector (24) is provided with a plurality of turning vanes (35) to swirl the mixture of fuel and air injected thereby.